1. Field of the Invention
Embodiments of the present invention relates to a liquid crystal display (LCD) device, and more particularly, to an LCD device capable of increasing the light efficiency of a backlight unit and a method for driving the same. Embodiments of the present invention are suitable for a wide scope of applications. In particular, an embodiment of the present invention is suitable for increasing the light efficiency of a backlight unit of an LCD.
2. Description of the Related Art
In general, a liquid crystal display (LCD) device, which is one example of a flat panel display, is being widely used in various applications because it consumes relatively less power and is lighter and thinner, compared to other display devices. Moreover, the LCD device may be manufactured in more various sizes of products the other display devices.
The LCD device relies on an optical anisotropy and a polarizability of liquid crystal molecules to produce an image. The optical anisotropy of liquid crystal molecules causes a refraction of light incident onto the liquid crystal molecules in accordance with an alignment direction of the liquid crystal molecules. The LCD device controls the amount of light incident onto the liquid crystal molecules. A backlight may be provided to project the light incident onto the liquid crystal panel.
FIG. 1 is a schematic side view of a related art LCD device. Referring to FIG. 1, the Related Art LCD device includes a liquid crystal panel 10 and a backlight unit 20 facing a surface of the liquid crystal panel 10. Not shown in FIG. 1, the liquid crystal panel 10 may include an array substrate and a color filter substrate. The array substrate includes a thin film transistor and a pixel electrode. The color filter substrate includes a color filter layer, a black matrix layer, and a common electrode. The array substrate and the color filter substrate face each other at a predetermined distance from each other. A liquid crystal layer is interposed between the array substrate and the color filter substrate. A voltage applied to the pixel electrode and the common electrode generates an electric field between the two substrates. Then, light from the backlight unit 20 is projected onto the liquid crystal display panel 10 to display an image.
The backlight unit 20 includes a light source unit 22 and a light scattering unit 24 disposed on the light source unit 22. The light source unit 22 generates light and may be formed of a cold cathode florescent lamp. The light scattering unit 24 provides the liquid crystal panel 10 with a light source having a uniform brightness distribution, and prevents the external appearance of the light source unit 22, such as the shape and geometric contours of the light source unit 22, from being displayed on a display surface.
Thus, the backlight unit 20 generates light from the light source 22. The generated light is scattered through the light scattering unit 24 to have a uniform brightness, and the scattered light is incident into the liquid crystal panel 10. The brightness of the light incident into the liquid crystal panel 10 is determined by the brightness of the backlight unit 20. In a system having a 5% transmissivity, the backlight unit 20 should generate brightness of about 200 nt to achieve a total brightness of up to about 100 nt. When a high brightness needs to be achieved in a particular area of the display, the total brightness of the backlight needs to be increased.
Thus, the related art backlight unit 20 consumes high power because a high voltage is applied to the light source unit 22 to increase the brightness. Moreover, the high power consumption causes an increase of the total temperature in the LCD device. Accordingly, causing defects of the components constituting the LCD device, or deteriorating the durability of the LCD device.